1.5 lakh fake AI citations slipped into scientific record in 2025: Study

BENGALURU: A surge of AI-generated fake citations has entered scientific literature, with a new study estimating that about 1.5 lakh fabricated references slipped into the record in 2025, most moving from preprints into peer-reviewed journals.

This is the central finding of a large-scale study by researchers at Cornell University, UCLA and UC Berkeley, which analysed 111 million citations across 2.5 million research papers published between 2020 and 2025 on arXiv, bioRxiv, SSRN and PubMed Central.

The study, titled 'LLM hallucinations in the wild', tracked citations whose titles could not be verified against major academic databases, including Semantic Scholar, OpenAlex and Google Scholar. By comparing post-2022 trends against pre-ChatGPT error baselines, researchers isolated the likely contribution of AI-generated hallucinations to the surge.

The steepest rise began around mid-2024, roughly 18 months after ChatGPT's public release, as AI tools evolved from writing assistants into citation-generation engines.

The contamination is not concentrated in obviously fraudulent papers. Researchers found that fake references are typically sprinkled sparsely across otherwise legitimate manuscripts, suggesting many researchers are copying AI-generated citations without verifying them.

Existing safeguards are failing. Nearly 78.8% of fake citations passed arXiv moderation, and among bioRxiv preprints later published in PubMed Central-indexed journals, 85.3% of hallucinated references made it into the final published versions.

Researchers warn the problem may now be self-reinforcing: as fabricated references embed themselves in open-access repositories and citation databases, future AI models trained on that corpus risk absorbing and reproducing the same hallucinations.

Study in Lancet too warns

In a separate study titled "Fabricated citations: an audit across 2.5 million biomedical papers" published in The Lancet, researchers found a sharp rise in fabricated citations in biomedical research papers.

The study, conducted by researchers from Columbia University and other institutions, analysed biomedical papers published between 2023 and early 2026. It found more than 4,000 fabricated references embedded across 2,810 peer-reviewed papers.

The audit found the rate of fabricated references rose dramatically over the three-year period. In 2023, roughly one in 2,828 papers contained at least one fabricated citation. By 2025, the figure had worsened to one in 458 papers, and by early 2026, it had climbed to one in 277 papers.

One of the most striking examples cited in the study involved a 2025 paper in an open-access oncology journal on ureteroileal surgical techniques. Researchers found that 18 of the paper's 30 verified references (60%) were fabricated. The authors linked the surge partly to widespread adoption of LLMs which are known to "hallucinate" fake citations.

Warning that fabricated citations could compromise clinical guidelines and systematic reviews, researchers urged publishers to introduce automated reference verification systems before papers are accepted for publication. Nearly 98% of the affected papers had not faced any publisher action at the time of the audit, the study noted.